The objective of this research is to distinguish different kinds of epidermal cells on the basis of their cell surface glycoproteins. The long-term goal is an understanding of the control mechanisms operative in epidermal differentiation and neoplastic transformation. A comparative study of the glycoprotein changes associated with various diseases of epidermal differentiation will be continued and completed, using the 125I-lectin overlay technique. The effect of various levels of extracellular calcium on growth and on surface proteins by lactoperoxidase iodination has been observed for two cell lines and will be examined for other cell lines (normal, preneoplastic and neoplastic). Calcium ionophores and calmodulin antagonists will be used to explore the mechanism of calcium action. In our current research, we have found nonmalignant cell lines to be insensitive to interferons, whereas the growth of tumor-promotable and malignant lines was inhibited. We next will study the effect of retinoids and tumor promoters upon cell growth and the associated cell surface changes. Chemical isolations will be pursued by lectin affinity chromatography and high-pressure liquid chromatography (size exclusion and chromatofocusing). Target molecules include the surface proteins most prominent at high calcium levels and also a constituent of crude immune interferon, not found in purified preparations, which we have observed to affect the cell surface. Antibodies will be prepared to the purified proteins.